The bomb squad was called in to investigate two suspected explosive devices found in Tauranga yesterday while police staff dealt with a third.
Senior Sergeant Mark Holmes said the Auckland bomb disposal squad was called to look at an old metal box reading "charge spotting mine" which was found on a property on Taupiri St, Maungatapu and a torpedo-shaped object found in the Go Bus depot on Maleme St, Greerton.
A Thunderflash, an explosive used by police in training exercises, was also found by police while executing a search warrant at a property in Hairini, Mr Holmes said.
"It's just a training explosive like what's used in mock battles basically a loud firework," Mr Holmes said.
Police officers were able to deal with it without the aid of the bomb squad, he said.
Police were alerted to the torpedo shaped object at the Go Bus depot on Maleme St about 4pm.
"Staff have taken the precaution of evacuating their own yard."
The bomb squad was called to investigate the object and later said it was "an inert 3-inch mortar".
Mr Holmes said the mortar was not dangerous and was probably a display piece.
The squad was also tasked with investigating the metal box found in Maungatapu.
A 73-year-old man, Lex Spencer, found the object while digging a garden path down a bank on his property on Tuesday evening. The box had the words "mine spotting charge C5" stencilled on it.
The man's son-in-law and next door neighbour Gary Marshall said the box could not have been more than 15cm underground.
Mr Marshall, who served in the South African Army, said he was not sure what the object was.
"It looks like an ammo box but it's not. We don't know if there are any more down there or not we just stopped there," he said.
The box was in army colours but Mr Marshall believed it was more likely an old naval relic.
"Looking at Google it looks like it's got something to do with submarine warfare."
Mr Marshall believed the box was far enough away from people and houses that it did not pose a threat to anyone so he waited until Wednesday morning to alert the police.
Tauranga police last night revealed the box was an empty ammunition tin.